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How to manage soil to prevent insects and pests

Followers of organic farming have for long promoted the idea that the likelihood of pest outbreaks is reduced if we practice organic farming, which includes establishing and maintaining healthy soil. Recent researches show that plant resistance to insects and diseases is linked to optimal, chemical, physical and biological properties of soil.

In farming, improvement of soil fertility is achieved through rotations, cover cropping and the application of animal and plant materials. Below are some of the main elements that can help reduce pest issues.

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Too Much Nitrogen

Vigorous, healthy plants that grow quickly are in a position to withstand pest damage.\However, over-fertilizing crops can actually increase pest problems. Research has shown that increasing soluble nitrogen levels in plants can decrease their resistance to pests, resulting in higher pest density and crop damage. For example, increased nitrogen fertilizer rates have been associated with large increases in numbers of aphids and mites.

Soil Food Web

Soils that are healthy and rich in organic matter and with a biologically diverse food web support plant health and nutrition better than soils low in organic matter and soil microbial diversity. In addition to supporting vigorous growth of plants better able to tolerate pest damage, healthy soils also contain many natural enemies of insect pests, including insect predators, pathogenic fungi, and insect-parasitic nematodes.

Different Organisms in soil

Soil and plant health are affected by soil’s physical condition, water holding capacity, level of compaction and drainage. The chemical aspects of soils (pH, salt content, availability of nutrients, etc.) can affect crop health and pest susceptibility.

There are several ways of improving soil health. In general, general, the focus should be on increasing soil organic matter to improve soil structure and to provide food for soil microbes that in turn make nutrients available to plants. Farmers should always rotate with cover and green manure crops in order to increase soil organic matter. Manure and compost can also be added to supply organic matter and to provide supplemental nutrients.

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Cultivation and tillage can be beneficial because it disrupts the life cycle of insect pests and can expose pests to predators and the elements. However, excessive tillage can accelerate the decomposition of soil organic matter and deplete the food source that soil microorganisms depend on, decreasing their ability to disrupt pests. Excessive and untimely tillage can also contribute to soil erosion.


Whether organic or synthetic, mulches, can help reduce insect pest problems. Plastic mulch is often used to speed early season crop growth that makes plants better able to tolerate insect feeding. Reflective mulch repels thrips and aphids and can reduce the incidence of insect transmitted virus diseases in vegetable crops.

Research has shown that straw mulch can suppress early season pests activity by creating a micro-environment that increases the number of predators like ground beetles, lady beetles, and lacewings. Mulching with straw can also reduce the pests ability to locate  plants.

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Health measures can be used to help prevent the introduction of pests onto the farm, to prevent the movement of pests within the farm, and to remove overwintering or breeding sites for pests on the farm. Here is what you should do to ensure sanitation is maintained.

  • Always try and plant pest-free plants; inspect plants brought onto the farm to prevent the introduction of pests.
  • Infested plants should be removed and composted, buried, or otherwise destroyed as soon as possible.
  • Removal of weeds and natural vegetation bordering crops may eliminate alternate hosts for some insect pests. Note that these areas may also harbor natural enemies; therefore, the farmer must carefully assess the potential threat from pest insects in these areas before mowing or removing any plants.
  • When working in an infested area, clean equipment and clothes before going to another area of the farm. Pests such as whiteflies and spider mites can be carried on workers’ clothes and spread to new areas.
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How to Improve Soil Fertility

The tips below will help improve your soil quality and ensure it is fertile and less likely to be susceptible to disease and pests:

Make sure your soil nutrient balance is right

 To see whether you have fertile soil, run a soil test to determine if the nutrient levels are correct. The test will show whether your soil is balanced and has the right amount of nitrogen, potassium and phosphorous. You can contact Oxfarm Organic Limited to test your soil.  Most plants thrive only when the soil has the right balance of acidity and alkalinity. If the soil is too acidic, or below 5.5 on a soil pH scale, you’ll need to add ground limestone. If it’s too alkaline, more than 7.5 on the pH scale, you should add soil sulfur. Using a drop spreader can help ensure you distribute either soil supplement evenly.

If you don’t test your soil on a regular basis, an easy way to check its quality is through a visual inspection. Soil should be composed of crumbs of various sizes that hold their shape while under a little bit of pressure. If it’s difficult to break up these crumbs, it’s an indicator that the soil is too hard.

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How and why to compost

 Composting is a great way to give back to the environment and your garden. Instead of throwing your grass clippings, coffee grinds or vegetable peelings in the trash, collect them and all of your natural food waste for your plants.  You can buy a composting system or make one at home using household items.

When you use compost in your garden it provides your plants with the microorganisms they need to be healthy. To ensure the compost will be effective, evenly spread a three-inch layer to the top of your soil. It will serve as a sort of protective insulation. Along with stimulating growth in your garden, composting can also help keep harmful insects away.

Add Manures for Nitrogen

One crucial element of farming that is often overlooked is the quality of the soil. High quality soil can ensure that your plants thrive and your farm sustains itself for years.

All livestock manures can be valuable additions to soil — their nutrients are readily available to soil organisms and plants. In fact, manures make a greater contribution to soil aggregation than composts, which have already mostly decomposed.

You should apply manure with care. Although pathogens are less likely to be found in manures from homesteads and small farms than those from large confinement livestock operations, you should allow three months between application and harvest of root crops or leafy vegetables such as lettuce and spinach to guard against contamination. (Tall crops such as fruits and trellised tomatoes shouldn’t be prone to contamination.)

However, because some nutrients from manures are so readily available, they are more likely to leach out of the soil (where they’re needed) into groundwater and streams. Also, if manures are overused, they can provide excess amounts of some nutrients, especially phosphorus. Because of this, it may be best to restrict fresh manures to heavy feeding, fast-growing crops like maize, and process additional manure by composting.

Avoid harsh chemicals and Fertilizers

 You want to keep bugs out of your vegetable garden, but some pesticides may damage your soil. Instead of spraying pesticides and chemicals, use your compost, mulch and bio-stimulants. Bio-stimulants include compounds and microorganisms. While you can’t avoid keeping out invaders all together, this combination will make your garden less vulnerable to insects.


Integrate rock phosphate

Crops that are grown in gardens with adequate phosphorous will be larger and healthier.

Rock phosphate contains nickel, iodine, zinc, boron and other properties that help your plants to grow. All you need is a bag of rock phosphate from your local gardening store to sprinkle over your garden. If you do that once every two years, you’ll notice a big difference in the quality of your plants, fruits and vegetables.

Now that you know some ways to help improve soil quality, you’re ready to start farming.